The first thing we did was to treat the pallet wood, to prevent it from weathering and falling apart. As we were growing food to eat, we did have some qualms about what we might use to treat it; but as we’ll see in the next step, we mitigated most of the effect of leaching somewhat anyway. We used a wax-based wood preservative, to keep the water out rather than provide a waterproof finish.

Next, we lined the frame with plastic. This prevents leaching of wood preservative into the soil (and of organic matter out of the soil!) and also insulates the bed from the cold a bit.

Fellow SW stalwarts Kevin and Brigitte had a lot of plastic bags left over from a woodfuel delivery, so we were able to take ten of these and staple them to the frame. A staple-gun might have helped, but wasn’t really necessary: we could dislocate the jaw on an ordinary office stapler, and use that to fix the plastic in place:

We attached two bags on each side, then laid a ninth and tenth down over the gap in the very centre.

We then put the frame where we wanted it to stay, and filled it with soil. A 1m2 bed, 40cm high, can take 400l of soil with ease (pedantic mathematicians should be aware that a given volume of soil will compact down under its own weight!) As we didn’t have easy access to decent topsoil, we mixed around 200l from our compost bin with 180l of organic compost, and added two bags of silver sand to make it less claggy. This mix is probably still a bit rich and still rotting, so we hope to add nitrogen with broad beans as one of our first crops.

Note that nearly 400 litres of soil have compacted, so it’s still shy of the top of the frame.

Finally, we assembled a bamboo frame over the bed, using old tennis balls (given away, having lost their bounce) at the corners. This permits us to add netting if we want, and in the first instance to put some wire mesh around the bed to prevent our cat from using it as a toilet, or simply as something to sharpen her claws on. We also put some fleece down earlier this week, to help warm the soil prior to today’s planting.

Here’s the finished bed:

Our completed raised bed, with mesh and fleece.

And I promise that this is the last post on raised bed DIY, although I hope to report back later in the year on how our square-metre gardening is going; assuming it’s going well!